3.1 Energy demands:
Energy needs - Nearly everything requires energy and a way to use energy is by transferring it from one energy store to another. Systems that can store large amounts of energy are called energy resources. The major energy resources available to produce electricity are fossil fuels, nuclear fuel, bio-fuel, wind, hydroelectricity, geothermal, tidal, water waves and the Sun. Ultimately, all the energy on Earth originally comes from the Sun but has been stored as different energy resources. Energy is needed in:
- homes - for cooking, heating and running appliances
- public services, eg schools and hospitals - running machinery and warming rooms
- factories and farms - operating heavy-duty machines and production chains
- transport - buses, trains, cars and boats all need a fuel source and some trains and trams connect to an electricity supply
Global energy consumption –
Most of the electricity generated globally is still produced by fossil fuels. This is partly due to:
- The high power output fossil fuels give compared to other energy resources, like wind and water waves.
- The existing infrastructure for extracting, transporting and processing fossil fuels - this makes fossil fuels cheaper than setting up new alternatives.
The recognised impact on the environment of burning fossil fuels has caused science and society to develop the use of renewable energy resources and make machines more efficient.
- In some developed countries, nuclear power stations are a growing form of electricity generation. Nuclear fuel can release large amounts of energy compared to fossil fuels and does not emit carbon dioxide. However, the radioactive waste that is produced is difficult to store and dispose of.
- Other factors that could influence governments’ decisions about the use of energy resources are political and economic pressures. For example, countries where the economy is heavily based on extracting and exporting oil, have a strong interest in fossil fuels to be largely used in electricity generation. In order to compete with more developed countries, growing countries like China need a large power output to keep growing their industry. This means they are likely to continue using fossil fuels and developing the use of nuclear power, alongside increasing supply from renewable sources of energy.
Conventional power stations - About three-quarters of the electricity which is generated in the UK comes from power stations operated by fossil fuels.
There are four main stages:
- Fuel is burned to boil water to make steam
- Steam makes a turbine spin
- Spinning turbine turns a generator which produces electricity
- Electricity goes to the transformers to produce the correct voltage.
The National grid uses power lines to connect power stations to the consumers. These include homes, factories, offices and farms.
3.1 Energy demands, 3.2 Energy from wind and water AND 3.3 Power from the sun and the Earth:
3.4 Energy and the environment:
- Power stations that use fossil fuels or nuclear fuel are very reliable sources of energy. These two types of station provide much of the country’s electricity. They operate almost continuously. When additional power is needed, gas power stations are usually used because they will come on very quickly and start generating electricity almost immediately.
- The fuel for nuclear power stations is relatively cheap, but the power stations themselves are expensive to build. It is also very expensive to dismantle, or decommission, old nuclear power stations at the end of their useful life and the highly radioactive waste needs to be stored for millions of years before the natural activity will reduce to a safe level.
- Water power, eg tidal and hydroelectricity, is reliable and predictable because of the Moon causing the tides and rainfall filling reservoirs. They can also be used to supply additional demand. But many of the renewable sources are unreliable, including wind and solar energy, and cannot respond to increased demand - sunny and windy weather cannot be guaranteed.
- Renewable resources have no fuel costs, but the equipment used is expensive to build.
3.5 Big energy issues:
The energy debate
The energy question affects us all deeply, but there is no "right" view on it. You need to consider the different solutions proposed, and ask yourself what is at stake for the different interest groups (for example consumers, politicians, LEDCs and MEDCs).
Here are some of the arguments:
- Many scientists, governments and international bodies (but not all) accept the greenhouse effect and global warming theories. Some argue that the greenhouse effect, and the extent to which greenhouse gases contribute to it, have both been exaggerated. Some argue that the predicted rises in atmospheric temperatures and sea levels are overestimated.
- Environmental campaigners argue that oil companies have contributed to environmental problems. Some activists even claim that wars in the Middle East were influenced by Western governments and oil companies' plans to get access to oil reserves.
Vidraru Dam, Vidra, Romania
- On the other hand, many representatives of oil companies and industries that use a lot of energy argue that environmentalists have exaggerated the extent to which fossil fuels pollute the atmosphere, and the impact this will have on the environment.
- Most governments have promised to reduce greenhouse gasses by signing up to the Kyoto Protocol. But the United States - the world's biggest greenhouse gas emitter - refuses to ratify the treaty.
- Some groups - environmentalists included - campaign against certain types of alternative energy generation. For example, dams built to produce hydroelectric power flood large areas - impacting on local people, wildlife, vegetation and hydrology. Tidal barrages could alter the look, behaviour and ecology of estuaries, such as the Severn, and might cause pollution problems. Some people oppose wind farms on the grounds that they are ugly and noisy and a hazard to wild birds.
That's the end of the topic!
Drafted by Kin (Physics)